1. Field of the Invention
This invention lies in the field of ignition systems for motor vehicles. More particularly, it concerns a self-contained device by means of which the operator of a motor vehicle may selectively check the potential appearing at the gaps of the spark plugs, while the engine is running, to determine the condition of the ignition system.
2. Description of the Prior Art
It is well known that the spark plug in the internal combustion engine provides the sparks necessary to ignite and burn the air-fuel mixture compressed in the cylinder of the engine. It is well known also that the efficiency of the ignition system in igniting the air-fuel mixture, synchronously, with the piston movement, can be affected seriously by many factors, concerning the ignition potential generating means, or the wiring of the ignition system, or the condition of the spark plugs. For example if the spark plug has deposits of carbon over the surface of the insulator of the high potential electrode, there will be conduction of current to ground through the surface layer of carbon, which will diminish the magnitude of the potential applied to the spark gap. This can delay or alter the intensity of the spark, to the point where engine failures may occur.
Furthermore there are strict requirements as to the gap length of the spark gap and other factors which if not adhered to will provide a less efficient spark generation and ignition.
If an operator of a motor vehicle finds his engine running "roughly", it may be due to the failure of one or more spark plugs in the system, or in the wiring, or in the distributor, etc. Failure of one spark plug to ignite properly on each cycle can cause loss of efficiency and waste of fuel and other undesired effects.
In motor vehicle garages and service agencies, they have expensive and complicated machines that can be applied to the engine, and to the ignition system, to diagnose such "rough" conditions of the engine. However, as a prompt and simple test to determine which, if any, of the spark plugs are faulty or whether it is in wiring, etc, there are no means available on the market for a operator to make this determination. Of course, he may stop the car, and individually check the spark plugs by removing them, or check for the presence of sparking potential by removing the conducter from the tip of the spark plug, and determining, when the engine is restarted, whether a spark is passing to that spark plug.
The device of this invention solves these problems by providing a very simple switch-controlled mechanism for checking visually the voltage applied on each spark pulse, to each of the spark plugs.